IM HAVING A PROBLEM THAT I CANT SEEM TO FIGURE OUT... WHEN YOU HIT THE GAS IM GETTING A BACKFIRE IN THE INTAKE.... WHEN YOU REV IT THE POWER DROPS AND SITS AT 3000 RPM LIKE ITS STRUGGLING AND THEN THE POWER PICKS BACK UP. ALSO FROM A DEAD STOP IT BOGS IF YOU TRY TO PULL OFF QUICKLY. AND THEN IT WILL STRUGGLE A LITTLE BIT TO GET GOING AGAIN... LIKE IT WILL BE MOVING, JUST EXTREMELY SLOWLY.... I JUST CHANGED THE PLUGS AND PCV VALVE, I CHANGED THE MAF A LITTLE WHILE AGO.... I CHECKED FOR ANY LEAKS ALSO... NOTHING.... WHAT COULD THIS BE? ALSO NO CEL!!

This is a video of a ticking noise coming from my IACV.. dunno if this has anything to do with this problem also?!?!
http://youtu.be/2kpaOggUxL0

This is the problem that im experiencing you can hear everything and see what my RPMS are at in this Video
http://youtu.be/KTiYPyzLu1Y

 

 

Do u have anyway of checking ur fuel trim? you could be running lean.
Did u check ur spark plug gap before installation?

EDIT: BTW here's ur kelp

 

YOUR TIMING MAY HAVE JUMPED OR YOU ARE TOO LEAN. ALSO THERE SHOULD NOT BE ENOUGH FUEL IN YOUR IM TO CREATE MUCH OF A BACKFIRE. IF IT IS VIOLENT, CHECK THE VACUUM LINE ON THE PRESSURE RGULATOR FOR FUEL.

 

ok.. this may be a dumb question.. but which line is that...
and sorry for the caps lock for all those that it bothered....
it was on from my password for something else and by the time i started typing this i didnt care at that point..

 

and how does your timing jump and how do i solve that if thats the issue... the problem existed before the spark plug change also .. sorry forgot to mention that... that was one reason i changed the plugs( even though it was time for them to be changed IMO anyway)..

 

He's talking about the timing chain jumping a tooth, which causes ur valves to open and close out of "time" or synch.

 

ok and if this is the case.... how do i figure this out...because it only does this when i rev it in neutral and the hesitation is only between 2-3500 rpm if im flooring it.... and speaking of flooring it.. if it is between this rpm range (even in the higher gears) if i floor it it just will make noise. MEaning you can hear the intake sucking its life away but there is no power and the car wont go anywhere until i come off the gas.
also i just removed the fuse for my fuel pump and the car ran for a good 4 mins before it cut off. i was told that it should only go for a few seconds.
Also ive been getting $h!tty gas milage..

 

As a last resort, you would have to pull the timing cover from the front of the motor and check all your timing marks on the crank and all 4 cams. On the rear fuel rail is the pressure regulator. Pull the SMALL line off and check for fuel in the hose. That is the vacuum line and should not have any fuel in it. Have you scanned for codes yet? I cant imagine backfiring through the intake and not getting any codes.

 

OK ill look at the FPR tomorrow... But no... NO codes.. not when i connect it to the OBD and not even when i do it manually through the ECU... Nothing... thats why im so damn confused..

OK so if there is fuel in that line.. then what??? DOes that mean the FPR is bad??? Fuel Pump??? Or what?

 

It would mean your FPR is bad and needs replaced. Diagnosing EFI is not my strong point, and I'll be the first to admit it.

 

Use the screwdriver-scope method to find whats ticking.

 

My 99 was backfiring out of the intake under hard acceleration. I had a aftermarket intake and man was it loud. It would pop multiple times followed by power loss. It wasnt throwing any codes so I started replacing stuff until I figured it out.

Turned out to be one of the ignition coils. I dont know which one it was.. but I replaced the entire set. Got all 6 OEM coils on ebay for $250 and that took care of the problem.

I about went insane trying to figure it out. Might be worth giving it a shot!

 

yea thats seeming to be the general concencus.... So ill be doing that again

 

Do you have a hard start?
Sounds to me like a leaky injector(s)
Pull the plugs and have a homie crank the engine if fuel sprays out replace the injectors

 

i do have a hard start

 

What's ironic is my 97SE is doing a very similar problem however it doesn't lag when revving like yours or make weird back fire sounds.

My EVAP on the intake manifold does make a clicking noise every now and then and my car does have a pretty hard time starting sometimes. Let me know what you figure out. It could be a future problem for me in the making.

 

soon as im back to 100%... i got you.

 

Sorry to bump this, It's been a while and I was wondering if any conclusion ever came from this. My Max has now started to do almost exactly what yours was doing then. It's not quite as bad, but it does backfire through the intake under hard acceleration and it seems like it's misfiring shortly after the backfire.

I haven't tested the coils yet, but all 6 were replaced last July. I've also replaced the MAF and checked the Fuel pressure. Still can't figure out what's causing the misfires and backfires.

 

Your either jumped timing or you have a bent intake valve......

 

My guess would be a timing jump then. My timing tensioner is bad.

 

have you a conclusion for this problem?

 

If the Timing chain has jumped at all it will cause the valve stems to be slightly off in the combustion cycle. It can cause backfire from the intake, engine misfire and if it jumps enough teeth the car will more then likely not start.

 

I am not a mechanic and have little experience with engines like this but I am restoring a 1967 Camaro and experienced the same problem you are. I replaced the ignition coil which solved my backfire issue. Weak spark to the spark plugs will not ignite all the fuel leaving fuel in the chamber. When the piston comes back up there is too much fuel causing the backfire. Hope this helps.

 

An intake manifold leak can also cause these symptoms.

 

I had this issue last summer. I replaced the spark plugs and that seemed to fix it.

 

I'm going to be doing a few diagnostic tests over the week. I'll be testing coil packs, changing spark plugs and checking for intake leaks with a smoke machine before I start taking the timing chain cover off.

Regardless I need to change my timing chain tensioner because it is bad. The car backfires and run likes crap sometimes and runs fine other times. It's rather puzzling.

 

Did you turn the screw on the IACV that will give you a ticking noise and some bad mileage. This is also the other way to go leaner. I am assuming there might be to much gas going in the chambers causing the car to wanna stumble completly dead. I would check the hoses for vaccum leaks,fuel injectors,FPR I am leaning towards this.

 

Thanks for the heads up. I haven't touched the black screw on the IACV no. So if I turn the black screw on top of the IACV it will lean out the fuel?

 

I will say yes, you will have to know which way to turn it counterclock-wise or counter clock. This will really change the RPMS at idle.

 

My car is idling at the correct 700RPM though. I don't want to mess with the idle if it's set correctly.

 

Does it tend to run like crap when the car is cold? Then when it warms up it runs a little better?

 

Sorry i was a douche for not posting on this when i finally got the car to run the was it was supposed to and i might add that she is back to beast mode where she belongs... Anyway... what my issue seemed to be was a combination of a clogged IACV and bad coils. But there were no codes... The problem got a little better once i cleaned the IACV but everything was back to 100% after i changed the coils. But with my experience i would start with plugs first then by checking everything connected with the intake ie Maf iacv etc before going to the coils.. If cleaning the IACV doesnt solve the problem then go to coils. Some guys were saying to check the FPR and in your case after checking those other issues that might be where to look next. But for me i didnt have to go that far.

Hope this helps